In the graphic arts field an image formation system which provides a high contrast photographic property is required to achieve improved reproduction of line images or continuous gradation images formed of half tone dots.
For this purpose, a special developing solution, called a lith developer, has heretofore been used. A lith developer comprises hydroquinone alone as a developing agent. In order to prevent the inhibition of the effect of infectious development, a lith developer contains a sulfite as a preservative in the form of an adduct with formaldehyde so that the concentration of free sulfite ions is extremely low. Therefore, this is seriously disadvantageous because a lith developer is extremely subjected to air oxidation and cannot be stored for more than 3 days.
The method for providing a high contrast photographic property with a stable developing solution as described in U.S. Pat. Nos. 4,224,401, 4,168,977, 4,166,742, 4,311,781, 4,272,606, 4,211,857 and 4,243,739 proposes the use of a hydrazine derivative. In accordance with this method, photographic properties with a high contrast and a high sensitivity can be obtained, and a high concentration of sulfite can be present in the developing solution. Therefore, the stability of the developing solution to air oxidation can be drastically improved from that of a lith developer.
However, the above-mentioned method comprising the use of a hydrazine derivative is disadvantageous in that the pH value of the developing solution is higher than that used in a conventional lith developer and it tends to fluctuate. This results in uneven photographic properties.
In order to overcome these difficulties, U.S. Pat. No. 4,269,929 proposes that an amino compound be incorporated in an alkaline developing solution comprising a dihydroxybenzene developing agent and a 3-pyrazolidone developing agent to improve the activity of the developing solution, whereby a hydrazine derivative can easily provide a higher contrast and exhibit the effect of sensitization with a developing solution yet having a low pH value.
However, even in this process, the pH value of the developing solution cannot be lowered to such an extent that it does not fluctuate under the ordinary conditions of storage or use.
Furthermore, an amino compound acts as a solvent for silver halide. (For further details, reference can be made to C. E. K. Mees, The Theory of the Photographic Process, 3rd Ed., p. 370, and L. F. A. Mason, Photographic Processing Chemistry, p. 43.) Therefore, the development process described in the above cited U.S. patent which comprises the use of a large amount of an amino compound tends to result in a disadvantage called silver stain in the art. In a process which comprises supplying a replenisher into a development tank, dependent on the area of a silver halide photographic film being developed in e.g., an automatic developing apparatus, silver stain means a disadvantageous phenomenon in which after use for a long period of time the developer releases silver halide by elution which is then deposited and attached to the tank walls of the automatic developing apparatus or rollers for conveying the film in the form of silver which is later transferred to the film to be subsequently developed.
In order to eliminate silver stain, a compound which exhibits an effect of providing a high contrast but does not act as a solvent for silver halide must be used. However, compounds suitable for this purpose are not known.
In the course of the preparation of film for a printing plate, a so-called block copy or a silver halide photographic material comprising a paper support, e.g., a light-sensitive material for photographic processing (hereinafter referred to as a "photographic printing paper") is used besides the above-mentioned superhigh contrast light-sensitive material. (Paper supports herein include a so-called resin-coated paper comprising a paper coated with polyolefin on one or both sides thereof.)
These light-sensitive materials have heretofore been processed with their exclusive developing solutions. However, the installation of numerous automatic developing machines corresponding to the number of the kinds of the light-sensitive materials to be processed requires great expense.
It has therefore been desired to process the light-sensitive material comprising a paper support and the superhigh contrast light-sensitive material suitable for photographing line or half tone images with the same developing solution.
However, it was found that the use of a large amount of the above-mentioned amino compound results in the development of color stain due to the penetration of the developing solution through a cut edge in the silver halide light-sensitive material comprising a paper support. It has therefore been desired to provide a compound which exhibits the effect of providing a high contrast but eliminates color stain on a photographic paper. However, compounds suitable for this are not known.